This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The primary objective of this study is to determine in the non-thymomatous MG patient population studied whether ETTX combined with prednisone therapy should be preferred to prednisone therapy alone. Secondary Objectives: The secondary objectives are (i) to determine the efficacy of the therapies by documenting their effects on myasthenic weakness and (ii) to determine their safety by documenting total exposure to prednisone and by recording the Trial Specific Adverse Events (TSAEs) and Adverse Symptoms (TSASs). Importantly, we shall also investigate whether outcomes vary between different subgroups by the following planned sub-group analyses: Use of corticosteroids vs. none prior to entering the study Male versus female Age 40 years at disease onset, (because of documented differences in HLA class and thymic pathology in these groups) Study design: The study is a multi-centered, Single Blind, Randomized, two-armed treatment trial. The duration of a subject's participation in this study will be a minimum of 36 months and a maximum of 51 months.